nupedia2018fandomcom-20200215-history
Birthday-number effect
The birthday-number effect is the subconscious tendency of people to prefer the numbers in the date of their birthday over other numbers. First reported in 1997 by Japanese psychologists Shinobu Kitayama and Mayumi Karasawa, the birthday-number effect has been replicated in various countries. It holds across age and gender. The effect is most prominent for numbers over 12. Most people like themselves ; the birthday is associated with the self, and hence the numbers in the birthday are preferred, despite the fact that they appear in many other contexts. People who do not like themselves tend not to exhibit the birthday-number effect. A similar effect, the name-letter effect, has been found for letters: people tend to prefer the letters that are part of their name. The birthday-number effect and the name-letter effect are significantly correlated. In psychological assessments, the Number Preference Task is used to estimate implicit self-esteem. There is some evidence that the effect has implications for real-life decisions. One lab study revealed an increase in a favourable attitude towards prices when they were secretly manipulated to match subjects' birthday dates, thus resulting in a higher chance of purchase. However a second study using birth year as price did not lead to the same result. A study of the liking of products found that participants with high self-esteem liked products better if the product names unknowingly involved their birthday number and letters of their name. Some field research into the impact of the birthday-number effect on bigger life decisions (e.g. where to live) is controversial. Background Throughout history, societies have had numbers they consider special. For example, in ancient Rome the number 7 was auspicious, in Maya civilisation the number 13 was sacred, in modern-day Japan people give three, five, or seven gifts for luck, and in China the number 8 is considered lucky and 4 is avoided whenever possible. In Western cultures the number 13 is often considered unlucky, hence the term triskaidekaphobia, fear of the number 13. Controlled experiments with numbers date back to 1933 when the researcher Dietz asked Dutch people to name the first number to come to mind between 0 and 99. The number 7 was mentioned most, as it was in various later replicas of the study in other countries. They argued that for this type of task, participants produce answers such that they appear to comply with the request for a spontaneous response. They speculated that the other numbers appear too obvious and that 7 is unique among the numbers from 0 to 9: it has no multiples among these numbers and neither is it a multiple of any of these numbers. However, young children do not apply this strategy and 7 does not come out on top in children of age eight and nine. }} The number 7 also came out on top in studies that asked people to name their favourite number. In an online poll by Alex Bellos, a columnist for The Guardian, more than 30,000 people from all over the world submitted numbers, with 7 the most popular. All numbers under 100 were submitted at least once and nearly half of the numbers under 1,000. The brain also appears to process odd and even numbers differently: measuring reaction speed researcher Hines discovered that it takes people longer to judge an odd number to be odd than an even number to be even. }} Marketing researchers King and Janiszewski investigated number preference in a different way. They showed undergraduate students random numbers and asked them to say quickly whether they liked the number, disliked it, or felt neutral. The number 100 had the highest proportion of people liking it (70%) and the lowest proportion of people disliking it (5%). The numbers 1 to 20 were liked by 9% more people than the higher numbers; the numbers that are the result of rote-learned multiplication tables (i.e. 2 × 2 to 10 × 10) were liked by 15% more people than the remaining numbers. The researchers concluded that number fluency predicts number preference: hence multiplication table numbers are preferred over prime numbers. The closely related field of letter-preference research dates back to the 1950s. In 1985, Belgian psychologist Nuttin reported the unexpected finding that people tend to disproportionately prefer, unknowingly, the letters of their own name. The name-letter effect has been replicated in dozens of follow-up studies in different languages, cultures and alphabets, no matter whether participants selected their preferred letter from a random pair, or picked the top six of all letters in the alphabet, or rated each individual letter. Nuttin predicted that because the driving force behind the name-letter effect is an unconscious preference for anything connected to the self, there would also be a birthday-number effect. Original study In 1997, researchers Shinobu Kitayama and Mayumi Karasawa observed that studies repeatedly showed that Japanese people do not seek to maintain and enhance their self-esteem, unlike Europeans and Americans. Whereas research with Western participants found that, on average, people falsely believe they are better than average, that they take credit for successes and blame others for failures, and that they overestimate the chances of good fortune happening to them, studies with Japanese did not reveal such self-enhancing tendencies. In addition, in cross-cultural studies, Japanese reported self-esteem to be hurt more by failures than boosted by successes, the opposite of what was reported by Americans. All these studies involved participants being aware that their self-esteem was being evaluated, and hence they are said to be measures of explicit self-esteem. This made Kitayama and Karasawa wonder. It seemed unlikely to them that Japanese have no positive feelings attached to their selves. They hypothesized that somehow Japanese do not allow these feelings to be detected overtly. To test this, they ran two experiments that hid the aim of assessing self-esteem, measuring instead implicit self-esteem. Because by definition implicit self-esteem is not accessible to introspection, measures of it do not rely on direct self-reports but on the degree to which objects associated with the self generate positive versus negative thoughts. The first experiment was a replica of Nuttin's 1987 study of letter preference, looking for an effect tied to letters of the participant's name. The second experiment involved numbers, looking for an effect tied to numbers representing the day of the month a participant was born (between 1 and 31) and the month of their birthday (between 1 and 12). Method For the letter experiment, they asked 219 Japanese undergraduate students to rate each of the 45 hiragana, part of the Japanese writing system, according to how much they liked it. For the number experiment, they asked 269 Japanese undergraduate students to rate the numbers between 0 and 49 on attractiveness. The number 49 was chosen as the upper limit to mask the true aim of the study, which 31 (being the maximum number of days in a month) might have hinted at. Likewise, the number 0 was included for disguise. Participants had to give ratings on a six-point scale, ranging from 1, if they disliked the number very much, to 6, if they liked it very much. Once done, participants were asked for various demographic data, including their birthdays. Results Analysis of the letter preference data revealed a name-letter effect: an enhanced liking for letters in the participant's own name. Analysis of the number preference data revealed a birthday-number effect. For each number, the researchers first calculated the mean liking by participants who did not have that number in their birthday. These means served as a baseline. For each participant 50 relative liking scores were computed between the baseline of a number and the actual preference. }} The mean liking scores for different types of numbers showed that participants disproportionately preferred numbers in their birthday. The effect was stronger for higher numbers, over 12, than for lower numbers. The effect was weakest for males and their birth month (only a 0.03 difference from the mean), and strongest for females and the day of their birthday (0.77 difference with the mean). Overall, women showed a greater liking for the numbers in their birthday than men did. Explanations Kitayama and Karasawa concluded that the patterns in the findings from both experiments were most consistent with the hypothesis that the preference is due to an attachment to the self. These feelings leak out to stimuli that are closely associated with the self, not just names and birthdates, but also, implicitly, their constituent letters and numbers. Finch and Cialdini, for example, manipulated some participants into thinking they shared their birthday with Rasputin. These people rated him more favourably than the control group. }} The researchers suggested that the effect is stronger for higher numbers because in daily life these numbers are less saturated with other meanings, other than their associations with birthdays. An alternative explanation for the birthday-number effect that had to be tested is mere exposure. If it were true that the numbers in one's birthday are used disproportionately in one's daily life, then the preference for numbers in one's birthday could simply be a preference for what is most frequent. Zajonc found in his 1960s and 1980s lab studies that familiarity can strongly influence preference, and coined the term "mere exposure effect". But Kitayama and Karasawa argued that even if people did see numbers from their own birthday more, this would still be negligible in comparison to the overall quantity of numbers they encounter in daily life. }} This is in line with the argument other researchers have used to rule out mere exposure as an explanation for the name-letter effect. Kitayama and Karasawa concluded that Japanese people do indeed have warm feelings towards themselves, just like Americans and Europeans, but that these feelings are masked when explicitly asked for. They speculated that the reason for this masking lies in the Japanese tendency to attend to negative, undesirable features by way of improving the self. Subsequent studies By 2017, Kitayama and Karasawa's original study had been cited in over 300 scientific papers.